Soft contact lenses are popular and often more comfortable to wear than contact lenses made of hard materials. Malleable contact lenses made of silicone based hydrogels can be manufactured by forming a lens in a multi-part cast mold where the combined parts form a topography consistent with the desired final lens. A first mold part can include a convex portion that corresponds with a back curve of an ophthalmic lens and a second mold part can include a concave portion that corresponds with a front curve of the ophthalmic lens.
A typical cast mold process involves depositing a monomer material in a cavity defined between optical surfaces of opposing mold parts. The mold parts are brought together to shape the lens formulation according to desired lens parameters. The lens formulation is cured, for example by exposure to heat and light, thereby forming a lens.
Following cure, the mold parts are separated, a process sometimes referred to as demolding. Typically, the demold process results in the formed lens remaining adhered to a remaining mold portion. Exposure to a hydration solution will typically hydrate the newly formed ophthalmic lens and facilitate its separation from the remaining mold part.
Design variations for each lens are limited to the design of the cast molds used to form the lenses. Consequently manufactured designs are usually limited to sizes and shapes conducive to wear by large numbers of people. It is possible to change out lens inserts for small runs of a specific lens design, however, the cost of tooling and the automated nature of manufacturing lines makes it economically realistic to only run relatively large batches of a certain lens design before switching over to a next lens design.
It is desirable therefore to have improved processes to facilitate contact lens release in aqueous solutions.